Method for staining sample

Abstract

A method for staining a sample includes the following steps. A test device is provided. The test device is sampled to obtain a sample. The sample includes a substrate, an active area disposed within the substrate and having a first doped substrate region and a second doped substrate region, at least one gate disposed between the first doped substrate region and the second doped substrate region, and an exposed shallow trench isolation embedded in the substrate and surrounding the active area. A first staining procedure is then carried out to selectively remove the shallow trench isolation to form a first void and to entirely expose the active area. A second staining procedure is subsequently carried out to selectively stain the first doped substrate region and the second doped substrate region to form a second void.

1. A method for staining a sample, comprising:
 providing a test device; 
 sampling said test device to obtain a sample, said sample comprising:
 a substrate; 
 an exposed shallow trench isolation embedded in said substrate; and 
 an active area disposed within said exposed shallow trench isolation and comprising a first doped substrate region and a second doped substrate region, wherein at least one gate is disposed between said first doped substrate region and said second doped substrate region; 
 
 performing a first staining procedure to selectively remove said shallow trench isolation to entirely expose said active area; and 
 performing a second staining procedure to selectively stain said first doped substrate region and said second doped substrate region. 
 
     
     
       2. The method of  claim 1 , further comprising:
 performing an inspection procedure to examine the first profile of said first doped substrate region and the second profile of said second doped substrate region. 
 
     
     
       3. The method of  claim 1 , wherein sampling of said test device is carried out by an ion beam. 
     
     
       4. The method of  claim 1 , wherein sampling of said test device is carried out by polishing said test device. 
     
     
       5. The method of  claim 1 , wherein sampling of said test device is carried out by cleaving said test device. 
     
     
       6. The method of  claim 1 , wherein sampling of said test device exposes said active area of said sample. 
     
     
       7. The method of  claim 1 , wherein said sample comprises a metal connection electrically connected to said gate. 
     
     
       8. The method of  claim 1 , wherein said sample further comprises a dielectric layer covering said active area, said first doped substrate region, said second doped substrate region and said shallow trench isolation. 
     
     
       9. The method of  claim 8 , wherein said first staining procedure removes said dielectric layer and said shallow trench isolation to form a first void surrounding said active area. 
     
     
       10. The method of  claim 1 , wherein said first staining procedure is carried out by using a fluoro-containing etchant. 
     
     
       11. The method of  claim 1 , wherein said shallow trench isolation entirely surrounds said active area. 
     
     
       12. The method of  claim 1 , wherein said second staining procedure is carried out at room temperature. 
     
     
       13. The method of  claim 1 , wherein said second staining procedure is carried out at 0° C. 
     
     
       14. The method of  claim 1 , wherein said second staining procedure is carried out in the presence of light. 
     
     
       15. The method of  claim 1 , wherein said sample comprises a PMOS.